1. Field of the Invention
The present invention relates generally to seals and more particularly to seals for rotatable or reciprocable elements which extend from a region of high fluid pressure to a region of low fluid pressure.
2. Description of the Prior Art
Forming a pressure-tight joint between a high-pressure vessel and the atmosphere when a moving element, such as a piston or rotatable shaft must be in communication with the atmosphere is one of the most difficult problems encountered by industries utilizing high-pressure fluids. There are two conventional types of seals for reciprocable and rotatable shafts. One conventional seal comprises a seal material which rubs against the shaft to prevent liquid from passing between the interface of the shaft and the seal. The sealing force increases as the pressure increases, which, at high pressures, results in excessive wear of both the shaft and seal. The other conventional seal has a small clearance between the shaft and the seal material to maintain an acceptable leakage rate between the shaft and seal. At high pressures the clearance increases due to a lack of rigidity of the seal material, which allows the leakage rate to increase beyond acceptable limits.
Accordingly, the art exhibits a need for a durable, low-cost seal for moving elements which extend from a high-pressure region to a low-pressure region.